meshtastic/docs/about/overview/radio-settings.mdx

---
id: radio-settings
title: Radio Settings
slug: /overview/radio-settings
sidebar_label: Radio Settings
sidebar_position: 1
---

:::info
Meshtastic is **not** LoRaWAN, nor TTN (TheThingsNetwork). Meshtastic uses the full spectrum frequency range designated to LoRa technology per region. This allows for several hundred possible frequency channels in the US region alone.
:::

![freq table](/img/LoRa-Frequency-Bands.jpg)

See [this site](https://www.rfwireless-world.com/Tutorials/LoRa-channels-list.html) for more information.

## Europe Frequency Bands

Power limits will generally be lifted in the software if `is_licensed` is set to `true` [HAM Mode](/docs/faq#amateur-radio-ham))

### 433 MHz

The maximum power allowed for Europe is +14dBm ERP ([Effective Radiated Power](https://en.wikipedia.org/wiki/Effective_radiated_power)).

The band range is from 433 to 434 MHz.

There are eight channels defined with a 0.2 MHz gap between them. Channel zero starts at 433.175 MHz

### 868 MHz (ISM Band)

The maximum power allowed for Europe is +27Bm ERP ([Effective Radiated Power](https://en.wikipedia.org/wiki/Effective_radiated_power)).

The band range is from 863 to 870 MHz.

There are eight channels defined with a 0.3 MHz gap between them. Channel zero starts at 865.20 MHz.

|Channel Number| Center Frequency|
|:---:|:---:|
| 10 |865.20 MHz|
| 11 |865.50 MHz|
| 12 |865.80 MHz|
| 13 |866.10 MHz|
| 14 |866.40 MHz|
| 15 |866.70 MHz|
| 16 |867 MHz|
| 17 |868 MHz|

## North America Frequency Bands

Power limits will generally be lifted in the software if `is_licensed` is set to `true` [HAM Mode](/docs/faq#amateur-radio-ham))

### 915 MHz (ISM Band)

The maximum output power for North America is +30 dBm ERP ([Effective Radiated Power](https://en.wikipedia.org/wiki/Effective_radiated_power)).

The band range is from 902 to 928 MHz.

There are thirteen channels defined with a 2.16 MHz gap between them. Channel zero starts at 903.08 MHz.

|Channel Number| Center Frequency|
|:---:|:---:|
| 00 |903.08 MHz|
| 01 |905.24 MHz|
| 02 |907.40 MHz|
| 03 |909.56 MHz|
| 04 |911.72 MHz|
| 05 |913.88 MHz|
| 06 |916.04 MHz|
| 07 |918.20 MHz|
| 08 |920.36 MHz|
| 09 |922.52 MHz|
| 10 |924.68 MHz|
| 11 |926.84 MHz|
| 12 |915 MHz|

## Data Rates

### Considerations

Various data-rate options are available when configuring a channel and are inversely proportional to the theoretical range of the devices. 

- **Spreading Factor** - How much we "spread" our data over time.
  - Each step up in Spreading Factor doubles the airtime to transmit.
  - Each step up in Spreading Factor adds about 2.5db extra link budget.
- **Bandwidth** - How big of a slice of the spectrum we use.
  - Each doubling of the bandwidth is almost 3db less link budget.
  - Bandwidths less than 31 may be unstable unless you have a high quality Crystal Oscillator.
- **Coding Rate** - How much redundancy we encode to resist noise.
  - Increasing coding rate increases reliability while decreasing data-rate.
  - 4/5 - 1.25x overhead
  - 4/6 - 1.5x overhead
  - 4/7 - 1.75x overhead
  - 4/8 - 2x overhead

### Predefined Channels

We have six predefined channels. These are the most common settings and have been proven to work well:

| Channel setting     | Alt Channel Name | Data-Rate           | SF / Symbols | Coding Rate | Bandwidth | Link Budget |
| :------------------: | :---------------: | :------------------: | :-----------: | :----------: | :--------:| :---------- :|
| Short Range / Fast  | Short Fast       | 6.8 kbps            | 7 / 128      | 4/8         | 250       | 137dB       |
| Short Range / Slow  | Short Slow       | 3.9 kbps            | 8 / 256      | 4/8         | 250       | 140dB       |
| Medium Range / Fast | Medium Fast      | 2.2 kbps            | 9 / 512      | 4/8         | 250       | 143dB       |
| Medium Range / Slow | Medium Slow      | 1.2 kbps            | 10 / 1024    | 4/8         | 250       | 146dB       |
| Long Range / Fast   | Long Fast        | 0.67 kbps (default) | 11 / 2048    | 4/8         | 250       | 148.5dB     |
| Long Range / Slow   | Long Slow        | 0.18 kbps           | 12 / 4096    | 4/8         | 125       | 154dB       |
| Very Long Range - Slow   | Very Long Slow       | 0.05 kbps  | 12 / 4096    | 4/8         | 31.25     | 160.1dB    |


:::note
The link budget used by these calculations assumes a transmit power of 17dBm and an antenna with 0dB gain. Adjust your link budget assumptions based on your actual devices. Data-rate in this table is actual measured but doesn't count mesh overhead, hops and re-transmissions.
:::

### Custom Settings

You may want to select other channels for your usage. The other settings can be set by using the Python API.

```shell
meshtastic --ch-set spread_factor 10 --ch-set coding_rate 4 --ch-set bandwidth 125 --ch-index 0
```

After applying the settings, you will need to restart the device. After your device is restarted, it will generate a new crypto key and you will need to share the newly generated QR Code or URL to all your other devices.

Some example settings:

| Data-rate  | SF / Symbols | Coding Rate | Bandwidth | Link Budget | Note                                                                     |
| :---------:| :-----------:| :----------:| :--------:| :----------:| :----------------------------------------------------------------------- |
| 37.50 kbps | 6 / 64       | 4/5         | 500       | 129dB       | Fastest possible speed                                                   |
| 3.125 kbps | 8 / 256      | 4/5         | 125       | 143dB       |                                                                          |
| 1.953 kbps | 8 / 256      | 4/8         | 125       | 143dB       |                                                                          |
| 1.343 kbps | 11 / 2048    | 4/8         | 500       | 145dB       |                                                                          |
| 1.099 kbps | 9 / 512      | 4/8         | 125       | 146dB       |                                                                          |
| 0.814 kbps | 10 / 1024    | 4/6         | 125       | 149dB       |                                                                          |
| 0.610 kbps | 10 / 1024    | 4/8         | 125       | 149dB       |                                                                          |
| 0.488 kbps | 11 / 2048    | 4/6         | 125       | 152dB       |                                                                          |
| 0.336 kbps | 11 / 2048    | 4/8         | 125       | 152dB       |                                                                          |
| 0.073 kbps | 12 / 4096    | 4/5         | 31        | 160dB       | Twice the range and/or coverage of "Long Slow", low resilience to noise  |
| 0.046 kbps | 12 / 4096    | 4/8         | 31        | 160dB       | Twice the range and/or coverage of "Long Slow", high resilience to noise |

The link budget used by these calculations assumes a transmit power of 17dBm and an antenna with 0dB gain. Adjust your link budget assumptions based on your actual devices.

These channel settings may have not been tested. Use at your own discretion. Share on <https://meshtastic.discourse.group> with your successes or failure.

## Cryptography

The pre-shared key (PSK) used by the devices can be modified.

- 0 = No crypto
- 1 = Default channel key
- 2 - 10 = The default channel key, except with 1 through 9 added to the last byte

Use of cryptography can also be modified. To disable cryptography (maybe useful if you have Ham radio license):

```shell
meshtastic --setchan psk 0
```